There are 2 different pages on that topic in Unity’s documentation:
http://docs.unity3d.com/Documentation/Components/SL-BuiltinStateInPrograms.html
http://docs.unity3d.com/Documentation/Components/SL-BuiltinValues.html
Is there a special reason for this? I can’t see why those couldn’t be merged into one, but wanted to ask here before reporting a bug.
Thank you.
IIRC, the first references solely types which also don’t depend on UnityCG.cginc. The second seems to consist of all standard values also including those added by UnityCG.cginc. (I’m not sure however, i don’t have unity access right now and haven’t tried using those values without UnityCG 
)
I think the first link is the original documentation. The second link was added for Unity 4 (I think, might have been 4.1) after we requested extra documentation on the variables Unity sets up.
I’m guessing it’s either not been cleaned up, or to allow links to the original page to still work.